New Year celebrations are taking place around the world with events also taking place around Ireland to ring in 2019.
Sydney and Hong Kong put on stunning fireworks displays in a spectacular welcome to the New Year, among the first in a wave of celebrations for billions around the world.
Australia's largest city organised its biggest-ever fireworks display, using a record amount of pyrotechnics as well as new effects.
Colours lit up the city's skyline for 12 minutes and dazzled the more than 1.5 million spectators who packed the harbour front and parks.
An earlier thunderstorm did not dampen the spirits of revellers who camped out at vantage points, some since the morning.
To mark the international year of indigenous languages in 2019, the harbour also hosted a ceremony celebrating Aboriginal heritage that included animations projected onto the bridge's pylons.
In Hong Kong, hundreds of thousands of revellers packed the streets on both sides of the city's Victoria Harbour for a spectacular 10-minute firework show.
Pyrotechnics bathed the city's skyscrapers in a dizzying array of colours accompanied by a score that included Auld Lang Syne sung in Cantonese, Mandarin and English.
Revellers were packed shoulder to shoulder on the densely crowded streets, many festooned with LED lights and sparkly glasses reading "2019".
In the Indonesian capital Jakarta, more than 500 couples tied the knot in a free mass wedding organised by the government, with fireworks shows cancelled out of respect for tsunami victims.
New Year's Eve celebrations were also called off in nearby Banten province, where the disaster struck on 22 December killing more than 400 people.
In Japan, locals flocked to temples to ring in 2019, as US boxing superstar Floyd Mayweather came out of retirement to beat Japanese kickboxer Tenshin Nasukawa in a multi-million-dollar "exhibition" bout outside Tokyo.
After suspending fireworks last yer, Dubai rang in the New Year back at the iconic Burj Khalifa.
The party atmosphere swept across major cities in Asia, Europe, Africa and the Americas as the clock ticked past midnight.
In Moscow, concerts and light shows were held across the Russian capital's parks and more than 1,000 ice rinks were opened for merrymakers.
In Paris, a fireworks display and sound and light show under the theme "fraternity" is set to go ahead on the Champs-Elysees despite plans for further "yellow vest" anti-government protests at the famed avenue.
In Berlin, music lovers will party at a concert at the Brandenburg Gate, but a popular German tradition of setting off fireworks to mark the occasion has been banned in some other cities over safety concerns.
Britain's capital London will usher in the New Year by celebrating its relationship with Europe amid turmoil over the Brexit referendum vote to leave the EU, with the fireworks display at the London Eye to feature music from the continent's artists.
Scottish capital Edinburgh's traditional Hogmanay celebrations will also take on a pro-European theme ahead of the year in which Britain is due to exit the union.
Meanwhile in Dublin, a special countdown concert will begin at the Custom House in the city centre at 8pm.